Réponses

2013-12-09T19:40:41+01:00
(7x-3)(6x+1)=42x²+7x-18x-3=42x²-11x-3
(-2-9x)(-4y-1)=8y+2+36xy+9x
(2x+3)(3-2x)=6x-4x²+9-6x=-4x²+9
(-10-3a)(2a-9)=-20a+90-6a²+27a=-6a²+7a+90